続々
ぞくぞく · zokuzoku · JLPT N2 · adverb
successively
🐜🐜 続 (tsuzu: to continue) doubled = one thing following another, one after another
続 means to continue or follow. Doubling it gives 続々, and the voiced reading ぞくぞく comes from the verb 続く (tsuzuku), to continue. It describes arrivals or events that keep coming in steady succession.